Supercroc Found (On My Own Science)

j Millbrook Press/Minneapolis

The photograph on page 46 is used with permission from © Reuters/CORBIS. Text copyright © 2006 by Sally M. Walker Illustrations copyright © 2006 by Philip Hood All rights reserved. International copyright secured. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means— electronic, mechanical, photocopying, recording, or otherwise—without the prior written permission of Millbrook Press, except for the inclusion of brief quotations in an acknowledged review. Millbrook Press A division of Lerner Publishing Group 241 First Avenue North Minneapolis, MN 55401 U.S.A. Website address: www.lernerbooks.com

Library of Congress Cataloging-in-Publication Data Walker, Sally M. Supercroc found / by Sally M. Walker; illustrations by Philip Hood. p. cm. — (On my own science) Includes bibliographical references. ISBN: 0-8225-6354-1 1. Sarcosuchus imperator—Juvenile literature. 2. Crocodiles, Fossil—Juvenile literature. I. Hood, Philip. II. Title. III. Series. QE862.C8W35 2006 567.9’8—dc22 2004017856 Manufactured in the United States of America 1 2 3 4 5 6 – DP – 11 10 09 08 07 06

To my intrepid explorers Maurice, Alexis, and Susan, without whom I would not have completed the journey —P. H.

A Dangerous Dinosaur Eater, 110 Million Years Ago A thirsty Ouranosaurus stood on the riverbank. The river seemed quiet and safe. Down the river, two eyes poked above the water’s surface. The dinosaur drank.

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Suddenly, a giant crocodile lunged from the water. The SuperCroc’s jaws snapped shut on the dinosaur’s head. The giant croc dragged the dinosaur into the water. The croc’s head whipped back and forth. Its sharp teeth ripped a hunk of meat from the dying dinosaur. The hungry crocodile gulped it down.

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For many years, SuperCroc ruled the river. But one day, it died. Animals ate its f lesh. Its bones lay on the river bottom. Layers of sand buried them. After thousands of years, the bones and the sand turned into stone. The bones had become fossils. Would anyone find SuperCroc’s fossils?

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Desert Discoveries, Ténéré Desert, Africa, 1965 Slowly, the riverbank changed. The climate changed too. The river dried up. The land became a desert in Africa.

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For many years, the wind blew sand across the land. The blowing sand scrubbed the rocky desert f loor. Fossils of trees and animals from long ago could be seen again. Some of the fossils belonged to SuperCroc.

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In 1965, a French paleontologist went to the Ténéré Desert in Africa. His name was Philippe Taquet. He was looking for fossils. Fossils taught him about animals and plants that lived in the past.

The Ténéré Desert thrilled Taquet. He found fossils everywhere! But he didn’t see SuperCroc’s fossils. Later, Taquet visited a museum in Niger. He saw a fossil of a crocodile skull. It had been found in the Ténéré Desert. The skull was 3 feet long! Taquet was surprised at how big it was. The skull of the largest living croc was only 2 feet long. Taquet wanted to study the skull. He had it sent to France.

Taquet studied the skull with a woman named France de Broin. De Broin was another paleontologist. She had other crocodile fossils. Her uncle, Albert-Félix de Lapparent, had found them in Africa in 1947. De Broin and Taquet compared their fossils. The two paleontologists made a surprising discovery. These bones were not like any other. No one knew about this kind of crocodile. It did not exist anymore. De Broin and Taquet named the crocodile Sarcosuchus imperator. Sarcosuchus means “f lesh crocodile.” Imperator means “emperor.” They thought their crocodile was larger than life, like a grand king.

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Paleontologists found more Sarcosuchus bones. One skull was 5 feet long! But no one found a complete skeleton. And no one found SuperCroc’s fossils. Taquet wondered how long Sarcosuchus was. He read about living crocodiles. He learned that their heads grow larger as their bodies grow. Taquet could measure a Sarcosuchus skull and figure out how long its body was. He measured and decided that Sarcosuchus could have been as long as a bus! Taquet wished he had a complete skeleton. Then he would know exactly what Sarcosuchus looked like.

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An Amazing Find Niger, Africa In 1997, Paul Sereno traveled to Niger, Africa. Sereno was a well-known dinosaur hunter. While looking for fossils, he saw a shape that looked like a crocodile head. It was the outline of a crocodile skull. Sereno knew this kind of skull. It belonged to a Sarcosuchus imperator. Three years later, he returned to Niger with a team of workers. Sereno’s team trekked across the hot sand. They were on a mission. They planned to dig out the giant croc’s skull.

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They measured the skull’s outline. It was 6 feet long! It was the largest Sarcosuchus skull ever found. They called it SuperCroc.

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Sereno’s team brushed sand off the skull. They marveled at SuperCroc’s long snout. It looked like the snout of a gharial. The gharial is a modern crocodile. Its skinny snout helps it catch and eat fish. But SuperCroc’s snout was long enough to crush a 5-foot-long fish!

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Some of Sereno’s students were part of his team. They searched around SuperCroc’s skull. They found more bones! Could SuperCroc’s whole skeleton be there? The team could hardly wait to find out. They dug into the rocky ground.

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Carving the rock took days. The team carefully chipped away the rock around the skull. They tunneled under it. But they left some of the rock around the skull. They didn’t want to accidentally chip off any small bits of fossil. That would ruin it.

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Next, the team soaked strips of burlap cloth in wet plaster. They wrapped the strips around the skull. The plaster dried into a hard, heavy covering. The covering would protect the skull from breaking. Sereno wanted to send the fossil to his laboratory in Chicago, Illinois.

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The next big step was loading the skull into a truck. Lifting the skull was tricky. One slip and the skull would smash to the ground. It took nine people to lift the 800-pound load. But they did it! Soon SuperCroc’s skull was on its way to the United States. During the following weeks, the team uncovered more of SuperCroc’s bones.

They also found other Sarcosuchus bones near SuperCroc. Together, all the bones made half a Sarcosuchus skeleton. The bones were shipped to Sereno’s lab. What would he learn from these fossils?

Questions and Answers Chicago, Illinois Sereno’s team of paleontologists worked on SuperCroc’s fossils and the other Sarcosuchus bones for many months. They carefully drilled away the plaster and rock. Sereno grouped the bones. He found part of the backbone but no tail. He wanted to know SuperCroc’s length. So he measured SuperCroc’s skull. From that, he figured out SuperCroc’s length. SuperCroc was almost 40 feet long! It was longer than any Sarcosuchus ever found!

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Next, Sereno wanted to see how SuperCroc’s mouth opened and closed. But he would never experiment with a SuperCroc fossil. It could break. Instead, he made a rubber mold of SuperCroc’s top and bottom jaws. From the mold, his team could make an exact copy of SuperCroc’s skull.

For the first time, Sereno got a close look at SuperCroc’s skull. SuperCroc’s eye sockets were on top of the skull. The tip of SuperCroc’s snout puzzled him. He had never seen anything like it. The tip was large and shaped like a bowl. The top jaw was a lot longer than the lower jaw. The jaws held 132 teeth. Some were longer than 3 inches.

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Sereno wondered if all crocodiles were like SuperCroc. He decided to look at modern crocodiles. They would help him understand how SuperCroc might have looked and acted. Sereno studied living crocodiles. He also talked to crocodile experts, such as Brady Barr.

Sereno and Barr watched crocodiles and even helped catch some. Sereno learned surprising things. Modern crocs bellow. But no living croc has a snout shaped like SuperCroc’s. Sereno thought that SuperCroc’s bowlshaped snout would have made a super-loud bellow.

Sereno watched modern crocodiles swim. Only their eyes and nostrils poked above the water’s surface. SuperCroc’s eyes and nostrils were in the same place on its head. Sereno believed that SuperCroc swam the same way.

Hidden by the water, a croc swims close to its prey without being noticed. Suddenly, the croc lunges from the water. The croc bites its prey and drags it into the water. Sereno thought that SuperCroc hunted this way too. And he was sure that SuperCroc hunted dinosaurs.

The teeth of SuperCroc and living crocs have the same shape. But SuperCroc had more teeth. And SuperCroc’s jaws were much more powerful than a modern croc’s jaws. Animal experts have figured out that SuperCroc’s bite was 18 times more powerful than a shark’s bite. That’s strong enough to chomp dinosaurs!

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What protected SuperCroc from a dinosaur’s sharp teeth? Sereno found the answer when he looked at SuperCroc’s bones. Behind SuperCroc’s skull, Sereno could see two rows of bony plates. These plates are called osteoderms. Each osteoderm covered part of the next one. They shielded SuperCroc’s soft body.

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Sereno saw that modern crocs also have osteoderms. Their osteoderms cover their backs and half of their tails like armor. Perhaps SuperCroc’s osteoderms did too.

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Sereno learned that crocodiles bask in the sun to warm their bodies. But if a croc’s body gets too hot, it can die. Crocs can’t sweat to cool off. Osteoderms keep a crocodile from overheating.

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Osteoderms have many tubelike blood vessels. The blood inside them gets hot when osteoderms heat up in the sun. The vessels carry hot blood away from the osteoderms. The blood f lows into cooler parts of the crocodile’s body. Sereno studied SuperCroc’s osteoderms. It was clear they worked the same way.

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Sereno wondered how old SuperCroc was. Crocodile experts suggested he look at SuperCroc’s osteoderms. Each year a croc grows, an osteoderm gets a new layer of bone. Sereno’s team used a microscope to look for and count the growth rings. The rings would also show how SuperCroc grew. Sereno knew that dinosaurs grew quickly. Did SuperCroc grow super fast too? The growth ring patterns showed that it didn’t. SuperCroc grew for about 40 years. Sereno thinks other Sarcosuchus imperator may have lived as long as 100 years.

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For Sereno and his team, SuperCroc’s bones were like a giant puzzle. Some pieces of SuperCroc’s puzzle were missing. But artists could fill in the empty spaces with models of the missing bones. Their fossil copies and fake bones were used to build a complete skeleton.

To make SuperCroc look alive, Sereno asked an artist for help. Gary Staab is well known for his lifelike models of creatures from long ago. Sereno told Staab what he had seen when watching living crocodiles. On his own, Staab learned more about crocodiles. Finally, he had enough information to make a life-size model of SuperCroc. The model has skin, scales, legs, toes, and eyes. After 110 million years, we can finally see how awesome SuperCroc was.

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SuperCroc’s 6-foot-long skull (left) makes the skulls of living crocs seem tiny. The skull of an adult Orinoco crocodile is less than 2 feet long.

SuperCroc was found in the hot, barren Ténéré Desert, near Gadoufaoua, Niger. This area of Africa is very different from the way it looked when SuperCroc was alive. Around 110 million years ago, a large river f lowed across a plain. Lush plants and tall trees grew along the riverbanks. Many kinds of animals lived there and were preserved as fossils. The fossil beds near Gadoufaoua are among the richest in the world. Some fossils found in Brazil appear to be Sarcosuchus imperator fossils. If so, they support the theory that 100 million years ago, Africa and South America were connected as one large continent. Perhaps future finds in Brazil will provide more evidence.

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Glossary climate (KLY-muht): the usual weather in a place fossils (FAH-suhlz): the remains of plants and animals that have turned into stone osteoderms (AW-stee-oh-durmz): f lat, bony plates found on a crocodile’s back and tail paleontologist (PAY-lee-uhn-TAH-luh-jihst): a scientist who studies extinct animals prey (PRAY): an animal that is hunted and eaten by another animal Sarcosuchus imperator (SAR-koh-soo-kihs ihm-PEER-uh-tuhr): an extinct kind of crocodile skeleton (SKEH-luh-tihn): the framework of bones in the body skull (SKUHL): the bony part of a head snout (SNOWT): the part of an animal’s head that includes its nose, mouth, and jaws

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Selected Bibliography Buffetaut, Eric, and Philippe Taquet. “The Giant Crocodilian Sarcosuchus in the Early Cretaceous of Brazil and Niger.” Paleontology 20 (February 1977): 203–208. Taquet, Philippe. Dinosaur Impressions: Postcards from a Paleontologist. Cambridge: Cambridge University Press, 1998. Sereno, Paul, Hans Larsson, Christian Sidor, and Boubé Gado. “The Giant Crocodyliform Sarcosuchus from the Cretaceous of Africa.” Science 294 (November 2001): 1516–1519. Sereno, Paul. “SuperCroc: A Dinosaur’s Nightmare.” National Geographic, December 2001, 84–89.

Further Reading Sereno, Paul. “SuperCroc: A Dinosaur’s Nightmare.” National Geographic, December 2001, 84–89. Sloan, Christopher. SuperCroc and the Origin of Crocodiles. Washington, DC: National Geographic Society, 2002. Walker, Sally M. Crocodiles. Minneapolis: Carolrhoda Books, Inc., 2004.

Websites DinoQuest Sahara http://www.nationalgeographic.com/dinoquest/ Paul Sereno and his team describe their work in Niger, Africa, in 2000. Photographs, notes from the field, and maps provide details on their incredible fossil discoveries, including the SuperCroc find. SuperCroc—Sarcosuchus imperator http://www.supercroc.com/ This site is the best resource for everything there is to know about SuperCroc.

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